Industry standards require medical device manufacturers to perform
implant-induced artefact testing in phantoms at a pre-clinical stage to define
the extent of artefacts that can be expected during MRI. Once a device is
commercially available, studies on volunteers, cadavers or patients are
performed to investigate implant-induced artefacts and artefact reduction
methods more in-depth. This study describes the design and evaluation of a
realistic head phantom for pre-clinical implant-induced artefact testing in a
relevant environment. A case study is performed where a state-of-the-art
piezoelectric bone conduction implant is used in the 1.5 T and 3 T MRI
environments. Images were acquired using clinical and novel metal artefact
reducing (MARS) sequences at both field strengths. Artefact width and length
were measured in a healthy volunteer and compared with artefact sizes obtained
in the phantom. Artefact sizes are reported that are similar in shape between
the phantom and a volunteer, yet with dimensions differing up to 20% between
both. When the implant magnet is removed, the artefact size can be reduced
below a diameter of 5 cm, whilst the presence of an implant magnet and splint
creates higher artefacts up to 20 cm in diameter. Pulse sequences have been
altered to reduce the scan time up to 7 minutes, while preserving the image
quality. These results show that the anthropomorphic phantom can be used at a
preclinical stage to provide clinically relevant images, illustrating the
impact of the artefact on important brain structures.Comment: 17 pages, 5 figure